Leveling valves of the aforementioned type are for example known from WO 2010/089089. Also, leveling valves of the aforementioned type are known from EP 2 806 194 A1.
Leveling valves of the known type are commonly used to regulate the vertical clearance of a vehicle such as a truck or other utility vehicle with respect to ground level. Depending on the load situation of the vehicle or depending upon dynamic forces acting on the utilization elements such as pneumatic suspension bellows of a vehicle, it is in certain situations necessary to increase or decrease the suspension level of the utilization elements. This is achieved by switching the leveling valve, in particular the valve arrangement, from its neutral position to either an “exhaust” switching position or an “air supply” switching position. Depending on the switching position, air will be exhausted from the utilization elements into the atmosphere, or will be supplied to the utilization elements from a source of pressurized air.
The leveling valve known from WO 2010/089089 focuses on possible ways of decreasing the number of sealing elements used inside a valve by making a non-rotatable valve disc axially movable inside a valve housing, wherein the two valve discs are pressed against each other by pressure prevailing in either a line connected to the source of pressurized air or in a line connected to the utilization elements.
In comparison to WO 2010/089089, EP 2 806 194 focuses on providing an improved leveling valve with better reactivity when switched, while at the same time providing a system which emits less noise.
A further desirable improvement for leveling valves would be that, in rare instances, when the air pressure on the supply side of the leveling valve breaks down, for example due to unforeseen damages to the fluid conduits, air is prevented from inadvertently flowing out through the supply port of the leveling valve, to maintain the inflation of the utilization elements. Ever increasing competitive demands in the industry favor solutions which are economically feasible while at the same time providing enhanced safety.